The two pieces of evidence that best support the idea that Harborough does not consider the dangers that may be hiding in the ocean are:
d. "The sea was, in a sense, absolutely smooth . . ."
e. "The surface of that ground-swell was without a wrinkle, polished and glossy like lacquer . . ."
These statements suggest a calm and deceptive appearance of the sea, which could lead to an underestimation of potential dangers lurking beneath the surface.